Lever arm shock absorber

Rotary vane

The first hydraulic shock absorbers were of the rotary vane pattern, the so-called Houdaille shock absorbers. These consisted of a cylindrical oil-filled body, bolted to the chassis. A lever arm was attached to the axle and inside the cylinder, this rotated a spindle carrying a vane or paddle. This vane had only a small hole in it, through which the hydraulic oil could pass. Resistance to flow through the hole provided the damping effect.

These were first developed by Maurice Houdaille around 1906,{{Cite book

This type was most common pre-war,{{Cite journal

Lever type

A design for a hydraulic lever arm shock absorber was patented by Georges de Ram in 1925, and the design was further developed during the post-war period.A better name might have been the 'piston' type, as both types described here use similar levers. This type of shock absorber had a large cast body containing a cylinder and pistons attached to a similar spindle and lever arm. Some used a pair of pistons for bump and rebound,{{Cite web

Integral wishbones

Many cars of this period began to use independent front suspension, often a double wishbone. The upper wishbone could conveniently also be used as the lever of the shock absorber, reducing the mass and bulk of the suspension, and also avoiding at least one ball joint. The spindle of the shock absorber now became the upper suspension pivot, usually double-ended.

One of the last mass-production sports cars to still use lever arm shock absorbers was the MG B.{{Cite web |url-status = dead |archive-url = https://web.archive.org/web/20120425161633/http://bhive.tierranet.com/200MGBfrontsuspensionpageone.html |archive-date = 2012-04-25

Obsolescence

During the 1960s, the lever arm was replaced by the telescopic shock absorber. This was encouraged by better roads and motorways, increasing average speeds and driver expectations of handling. The telescopic shock absorber dissipated heat more effectively, owing to its larger working volume of fluid and also the better ratio of surface area to fluid volume.

About the only area where lever arm shock absorbers still are actively used is tank suspensions, where their compact size and unique geometry allow them to be easily integrated with the suspension's torsion bars, and the massive tank chassis acting as a one huge heatsink alleviates the heat dissipation problems. Some designs of this type of shock absorber lend themselves well to their modification as an active suspension actuators, and at least one modern main battle tank (Russian T-14 Armata) is said to have this type of suspension.

References